STIMULATION OF MUSCLE AND NERVE 137 



polar stimulation, anodal closing contraction may 

 appear before cathodal closing contraction, a 

 reversal of the normal sequence. 



In degenerated nerve there is of course a total 

 loss of irritability, corresponding to the destruc- 

 tion of the axis-cylinder. 



GALVANOTROPISM 



Paramecium. Connect two non-polarizable 

 electrodes through a pole-changer with a dry cell. 

 On a glass microscope-slide make with wax an 

 enclosure about one centimetre square and a few 

 millimetres high. Place in this a little hay 

 infusion containing Paramecia. Bring near the 

 two opposite sides of the wax cell non-polarizable 

 electrodes, provided with a thick thread that shall 

 dip into the infusion. Examine the infusion with 

 a very low power. Close the key. 



Upon closure each Paramecium turns the an- 

 terior end of the body towards the cathode and 

 swims in that direction. In a very short time 

 the anodal region is free, and the Paramecia are 

 gathered at the cathode, where they remain so 

 long as the current flows. 



Change the direction of the current. 



The Paramecia now turn to the anode and 

 swim in that direction, but the anodal grouping 

 is less complete than the cathodal, and lasts but 



